History of the Tree Census

“In 1974 plant ecologist, Dr. Allen Gebben, and then recent Calvin graduate, John Ubels, laid out a 1. 72 ha grid system in the college’s northeast woodlot that now lies at the center of the Ecosystem Preserve. The grid consisted of 43 20 x 20 m quadrats that enclosed much of the old growth portion of the woodlot while avoiding conspicuous edge areas. In each of the quadrats Gebben and Ubels mapped and measured the diameter (diameter at 4.5’ on the trunk or dbh) of all woody stems in the ranges of 2” to 3.9” and 4.0” and above. The latter size range is commonly considered to define “trees” in forest ecology, and it is this group that has been measured regularly in the years since. In 1994, with the forest edge moving farther from the forest core, an additional 7 quadrats were added to the south and west of the original study area to bring the total area censused to 2.0 ha.” (Taken from the “Forest Community Study Plan” document).

Below you can see how DBH was measured for each tree.